ci: rename .lava-test to .lava-test-deqp to describe it correctly

ci: rename .lava-test to .lava-test-deqp to describe it correctly

.lava-test hidden job was setting the HWCI_TEST_SCRIPT variable to deqp
runner. But that is not always the case. When we run piglit traces jobs,
we use piglit-traces.sh instead, for example.

Splitting into:
- .lava-test-deqp (deqp-runner + deqp)
- .lava-traces (deqp-runner + piglit)
- .lava-piglit (piglit-runner + piglit)

Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>
Co-authored-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22065>